I got the idea for the game when I was reminded of an old meteor-shooter I used to play on Windows XP. I thought it would be fun to recreate that game dynamic while learning to use some new syntaxes and features of ES2015.
Pressing A or D will fire the left and right guns, respectively. The bullet trajectory is based on where the mouse cursor was at the time of firing. Falling red meteors that are intercepted by a bullet will explode in a bright orange ball. If a meteor reaches the city (currently a white strip along the bottom of the frame), that portion of the city will take damage, changing in color until it is completely dark -- destroyed.